Degenerative disc disease affects 65 million Americans. Up to 85% of the population over the age of 50 will suffer from back pain each year. Degenerative disc disease (DDD) is part of the natural process of growing older. Unfortunately as we age, our intervertebral discs lose their flexibility, elasticity, and shock absorbing characteristics. The ligaments that surround the disc called the annulus fibrosis, become brittle and they are more easily torn. At the same time, the soft gel-like center of the disc, called the nucleus pulposus, starts to dry out and shrink. The combination of damage to the intervertebral discs, the development of bone spurs, and a gradual thickening of the ligaments that support the spine can all contribute to degenerative arthritis of the lumbar spine.
When degenerative disc disease becomes painful or symptomatic, it can cause several different symptoms, including back pain, leg pain, and weakness that are due to compression of the nerve roots. These symptoms are caused by the fact that worn out discs are a source of pain because they do not function as well as they once did, and as they shrink, the space available for the nerve roots also shrinks. As the discs between the intervertebral bodies start to wear out, the entire lumbar spine becomes less flexible. As a result, people complain of back pain and stiffness, especially towards the end of the day.
Depending on the severity and the condition, there are many ways to treat DDD patients with fusion being the most common surgical option. The estimated number of thoracolumbar fixation procedures in 2009 was 250,000. Surgery for degenerative disc disease usually involves removing the damaged disc. In some cases, the bone is then permanently joined or fused to protect the spinal cord. There are many different techniques and approaches to a fusion procedure. Some of the most common are ALIFs, PLIFs, TLIFs, XLIFs (lateral), etc. Almost all these techniques now involve some sort of interbody fusion device supplemented with posterior fixation (i.e. 360 fusion).
Another spinal malady that commonly affects patients is stenosis of the spine. Stenosis is related to the degeneration of the spine and typically presents itself in later life. Spinal stenosis can occur in a variety of ways in the spine. Most of the cases of stenosis occur in the lumbar region (i.e., lower back) of the spine although stenosis is also common in the cervical region of the spine. Central stenosis is a choking of the central canal that compresses the nerve tissue within the spinal canal. Lateral stenosis occurs due to the trapping or compression of nerves after it has left the spinal canal. This can be caused by bony spur protrusions, bulging, or herniated discs.